Improvement in telegraphing



. cnolunfELL'FLEETWooij winner, ori LONDON, ENGLLANILV 'l specificati@ fel-ming pmftpf Leiters Patent N 78,495, aurea. .nine 2, 1868.

.To all whom it may concern.'

Be it known'that I, CROMWELL FLEET- WOOD VARLEY, of London, England, teurporarily residing, 'in 'New York, county of leuT York, and State of New York, haveinvented certain new' and useful Improvements in Electric Telegraphs; a'nd I hereby declare the following to b e ajull, clear, and exa-ct description of the saine.

The objects of my invention are to cut off the disturbance arising` from earth-currents, to obtain a high speedof signaling' through .long circuits, andshould the conductor become partially exposed, to preserve it from being eaten away by elcctrolytic action.

"No means, prior to my invention, had been devised for el'ectingfthe :first and third ot' vthese results. l have devised several other' methods less perfect than those hereinafter described, but all embodying' the general principle of my invention.

The invention consists ofthe arrangement. l

of Well-known apparatus, Whose action, being of an electric and magnetic character, cannot be explained oy drawings or models; but the accompanying diagrams and specification will enable those skilledin the art to under stand the invention.'

flhe telegraphic signals in'this iinventioxr V long cables obtained. The first plan is by means ot'an induction-coil. The cable, at the receiving end ofthe circuit, is' 4connected to the primary u'ire of. un induction-coil, and through it to the earth, lhe' secondary wire is connected to the telegraph-instrnmcnt.

. This emugcment is represented by Diagram 'Explanation et' its actionv'; 0n a current passingV through the primary wire of the induction-coil, the iron core becomes magnetized, and this magnetization produces a current in the secondary wire, which acts upon the telegraphic instrument.

NVhen the current iu the primary'wire lhas 4 reached its maximum force, and is llowing steadily through, the iron I core is magnetiz'ed v The earth-currents seldom passfro'm zero to their maximum and back aga-into zero (prior to changing sign) in lossv than live or six minutes, whilethe telegraphic signals are generally produced in a small fraction of a second. v

`With the former, although the currents lare often very strong, the rate ot' change of Y strength is extended over several minutes, and consequently the current in the secondary wire 'is very feeble, as its strength is mainly .dependent upon the rate vof variation of th magnetism ot'V the iroucore. Y The signaling cu'rionts lor impulses are much more rapid orsndden, and consequently the variation of the" magnetism oi' the iren core is much more sudden, and the currents generated thereby in the-'secondary Wire are comparatively pou-'erful and distinct.

Thus, then, suppose the earth to -send a.,

current through the line-say a positive current from the sending' to. thc receivingstationund to slowly niaguetize the iron core, and, for ease ot explanation, suppose this earth-ciu'rent to remu-inibr a til/fte steady and uniform in strength 1ct, new, the sending-stationrnm-ke asignal. In doing-so his battery adds its strength to or opposes the carth-ciu'rent, accordingly as the signal sent ditiont'o or subtructionirom the earth-current 'produces n @pid augmentation oril'imiultion of the-magngtism in the iron core, and thus produces 'n .ihstmct signal in the secondary lwire; Y

y For still further erplanation, suppose the the iron coil experience a rapi andanegative signal will be produced inthe secondaiywireconespondin g to the decrement strongly positive.

. the ordinary means.

earthcurrent to' kie-P, and have strcngt f of-1GO plusor positive, and the signal-current to have a strength of 10,.if a ositive' signal vbe sent, the 'current will rapi f rise at the` l receiving'end in theproportion of 100 to A1-10. v 'lLhis rapid increment oi-magnetismwlll "'"duoe a= positive signalzil fthe secondary wire," 'corresponding to the, increment 10.*1But'ifi negative signal 'be' sent,-the'n the battery. willbe opposed to'thefearth-current, ad the'cdr- ,rent'will rapidly fall at the receiving :end in 'I the 'proportion of 100 to 90,- the magnetism in (or negtive increment) 10a hough thecu-r- -rent t ougiitheglin'e or ca As the strength of vthose secondary signals-iis.

' ahnost entirely dependent upon the rate of-in'-4 crelnent and decrement of the'current through and as the slowest Aline yet 'the prim conetruoir need-notrequi're so much as half a second to produce a clear signal, while the f takes five Aminutes or six hundred, halfseconds, Lthe current arisingintlie second..

ary from the earth-current (which, al-v' t'houghassumedto'be ten times stronger,l is six hundredtimes slower) is=1= E10.V part only of the' strength of the signal, andthe @fede 'of the earth-current 'are consequently practcallycut on,

` When signalingthrugh a very long cable,

, a rapid snocessionof signalscharges the cable f and produces' an electric wave, which is a long while subsiding, and acts at the receiving end in l asom'ewhat analogous manner to the earthcurrent just described. This prevents signals frmbeing transmitted'in rapidsuccession by The above apparatus, which may be popu-A larlydescribed: as disentangling the short high-crested waves from the large' long swells,

enables clear distinct signals to be produced -*ii-idly one afterthe other.

he strength of the signals' through the cable or telegraph-circuit is produced by the rate of the incrementsand decrements of-curf rent, 'and not by the current-, itself; and, as

an imperfect illustration if the great earthcurrent through the .cab e be compared with an Atlantic swell whose height lis ve fathoms,

but spreading horizontally over ive or six,

v hundred fathoms, and whose sides will have an angle of, say', one hundred and seventyeight degrees, and if the signalsv bercoinpared with the ripples produced by the wind upon the back of the swell, and whose angles are each, say, sixty degrees, then lan vapparatus that will indicate these angles would scarcely notice the an gle' oi' one hundred and seventy-v eight degrees, which is nearly-a straightline,

(or one hundred' and eighty degrees,) while ythe small waves, with an angle each of sixty' degrees would 'be distinct, and such apparatus would iseatangle'the small signals from the decrease,-

le remains` swell,paying;` almostY no'v attentiori` lthe latter. Electric waves are entirely different from water waves; butthe illustration;v may V'serve to explain the action-of. thesformer` 'The second plan-ofseiiectingthef'abovc is 'more expensive in construction, but more perfeet in actiongigA large condenser is inserted in, v the." circuit at Vone or botli ends,` accord# ing. tothe .circumstances of the case; At the receiving end of the vline-I prefer the following .ngementziagmm No. 2,) whien gives a rapid rate bf-slgnaling. r

"- The cable is connected'to the'lene armature of the'condenser through the telegraphrel ceiying-instrument, andthe other armature is connected with the The cable is also conncctedto the earth by means of a resist-v ance-coil, which is best when made of a lon length of insulated, copperwire wound roun an iron core. n

' 0n acurrent running through the line or -cable,.it nds at the distant end ,two routes or-A channels, viz.,.the resistance-coil andthe condenser. @he condenser-route at the firstlinoment odors no other sensible resistance than vthat of the .receiving-instrument, while the other, owingv to the .magnetic .inertia of the iron core, offers at the first moment a cousiderz able resistance. TheA condenser is rapidly l charged, and, asv soon as it is` charged to the full force .or .potential of the current in .the

Y cable, all? the -rest of the electric'current goes throughthe resistance-coil'to'earth, and no more current isJ shown uponA the receiving-instrument. fIf, now, the potential in the cable.

-be reduced or increased alittle, the 'charge inY thecondenser is reduced'o'r increased in proportion, and ainegativc or positivesignal can be distinctly produced at pleasure, although.

the electric current. or' charge. in vthe line or cablehas not changed sign, but only varied` in strength. The resistance-coil between the cable and the earth'maybe dispensed with but then the little signabwave does not reach its'maximum so rapidly, and consequently the signals are not so-rapid. (Vide Diagram 6.)

only; but the disturbing action of the earthcurrent, however, is more felt when the condenser is only plaoed'atthe sending end, be-v cause the earth-current has tocharge the cable in addition to the condenser, all of which charging-current has to pass through the receiving-instrumcnt. `When thecondenser 'is used at the sending end ofthe cable or line (Diagram 3,) the cable is connected to the one rases armature ofthe condenser andthe telegraphkey to the ,other armature of the condenser.' An ordinary double or reversing laevis gen-l erally used, so that when the one is- 'depressed a positive charge is communicated to the condenser-armature attached to` it, and when l,the other is depressed a negative charge is co1n municated p it.

If the key had been connected .to the line or cable in the usual manner, a constant or permanent current would have-been produced through the cable so long as the contact was maintained, and this current would only begin ltc die away Whenthe contact with the battery was broken or reversed. But when the ccndenser is interposed inl the circuit, as described, so soon as the current from the battery has charged the condenser. the ,current from the condenser isv arrested, and'variations inthe length of the battery-contact beyond a "Ax: `l amount will produce Ano change in the amount f current thrown into or induced in the cab In this way great unifcrmity'and regniarity'of signals are obtained.

at the-sending end of the line it is sometimesl advisable to use a smaller condenser than at the receiring end, und higher battery'- 'iewer, because' the 'more sharp and `sudden the impulse is given the quickerwill the signal `fzrppear at the distant end.

,lf the dimensionsotvv the condenser be re-v' ducedsay halved-and the battery-power be yugmented in `the inverse ratio, then the shock prf impulse will be' the, same in amount, but

incre sudden, producing a rather more rapid signal at the distant end; but the disturbing action of theearth-currcnts is reduced as the, dimensions of the'condenser arereduced at' the receiving end. v

In some cases-such, for example, as Where the Mol-sc instrument is-used-it is advisable. to connect together the two armatures by means of a very large resistance, as shown in Diagram G-,sothat after the condenser is vcharged the vcurrent through the cable shall not entirely cease. Thus Vthe sharp,-sudden impulse 'of the condenser charges the cable, and would. producea dot, but not aline or dash.

The Weak current through the large resistance, however, maintains the current in the cable, anda dash is produced, the Morse armature being held down-by this weak curre1 1t so long Iasthe key is held down.

Gn-the' key being elevated, the charged condenser is connected to the ground, if the condenser be at the sending end; and indis- `charging itselfthe condenser produces a short, sharp current in the cable inthe opposite direction, which rapidly terminates the signal at the distant end of the 'cablei All cables are liable'to have their-insulatio impaired. When this is the case, and the copper conductor is exposed to the sea-water,

the copper is decomposed whenever a positive current is permitted to new from the copperinto the Water, forming chloride ci copper,

which 'is soluble, and diduses itself and decisi,V

away'.

If the cablehekept alwaysl negative water, the'action of the positive current nowthe wire from decompo'sitisi.v- To. ellect this I place a condenser at each end ofthe cable, (Diagram 7,) and also connect to the cal1e,thrcugh a large resistance( or long coil kof ne 'wire,) a battery whosepositive-Jpole is connected to the earth and negative pelote the ing into the wire from the water is te preserve resistance-coil.' This keeps thecable alvray's negative to the water, and yet;l the lsignals through itand the condensers areeither pcs;-

tive or negatire, at pleasure; Suppose `the signal-impulse to be a positive one, it Weakensthe negative character of thel charge in the cable and Yalscn-the distant condenser, and-:imma

'duced in the distantinstrument,

If the signal impulse be negative, it in creases the negative charge inthe cable. and" diately a corresponding positive signal is proalso in' the, distant condenser, and .therefore produces a negative signal :in the distant in strument, and thus, although positive and negative impulses 'are produced at the distant end, the cable has been only less ormore negative, but never positive, to the sca, and therefore, the'eonduetor has been constantly under the. preservative action of the negative current. Thus, then, the action of the condensers and battery has been-not only te cut off the en'ect of the earth L currents' and to expedite vthe transmissionoi' signals, but also to preserve the conductor of the cable from destruction, if

exposed tothe sea-water.

In Diagram 7 the 'place of the switches cr commutators is shown. These have been omitted. in the other diagramsto simplify them. These commutatore are of the ordinary well-known form common to most systems of submarine.telegraphing, and are not apart of this invention.

Having now described my invention, and the .manner in which theA same isl or may be carried into eifect,.what l claim, and desire to secureby Letters Patent, is-

In so arranging telegraphic apparatus asto Work by thew-'ariation of the increment purposes set forth.

4, ,Themse of 'a condenser at the sending tween the cable and the earth, as and vfor the end of'the oabe, with or without; resistance- Intestmonywhereofhave signed myn'ame, coils connecting its two-enrnrwfmlres, as and for to .this specification before two subscribing the purposes set. forth. Witnesses.

5. The use of a condenser at; each .end of the cable, the cable being. eonne'cted with G. E VARLEY. the ground through a resistance-coil and a battery, so as to keep the' cable yalways nega- Witnesses: A

tively electrified, as and for the purposes setA f W. BAILEY*7 forth. Y C. G. PAGE, Jr. 

